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By Alan Lightman

May 14, 2018

THE ORDER OF TIME By Carlo RovelliTranslated by Erica Segre and Simon Carnell Read by Benedict Cumberbatch 4 hours, 19 minutes. Penguin Audio.

There’s a passage in Carlo Rovelli’s lovely new book, “The Order of Time” — a letter from Einstein to the family of his recently deceased friend Michele Besso: “Now he has departed from this strange world a little ahead of me. That means nothing… The distinction between past, present and future is only a stubbornly persistent illusion.” Rovelli comments that Einstein was taking great poetic license with the temporal findings of his relativity theory, even to the point of error. But then the author goes on to say that the great physicist was addressing his letter not to scientists or philosophers, but to a bereft family. “It’s a letter written to console a grieving sister,” he writes. “A gentle letter, alluding to the spiritual bond between Michele and Albert.” That sensitivity to the human condition is a constant presence in Rovelli’s book — a book that reviews all of the best scientific thinking about the perennial mystery of time, from relativity to quantum physics to the inexorable second law of thermodynamics. Meanwhile, he always returns to us frail human beings — we who struggle to understand not only the external world of atoms and galaxies but also the internal world of our hearts and our minds.

From ‘The Order of Time’

Carlo Rovelli reveals his take on relativity, order and the human condition. Narrated by Benedict Cumberbatch.

The book is read by the British actor Benedict Cumberbatch, who has benefited from significant stage experience as well as starring in such films as “The Imitation Game” and the TV series “Sherlock.” Cumberbatch possesses a deep and rich voice and reads the text in a precise but unhurried manner, with the result that we feel as if we are getting an exposition by an erudite but gentle teacher.

The ancient Babylonians saw time as a wheel, repeating in cycles. Confucius likened the passage of time to the flow of a river’s stream. For the kabbalists, time is an illusion. Isaac Newton conceived of time as a rigid scaffolding erected by God.

Rovelli, who is a theoretical physicist at Aix-Marseille University in France and the author of the international best seller “Seven Brief Lessons on Physics,” explains how scientists in his field look at time, seasoning his book with quotes from the likes of Horace and Shakespeare and a fair measure of his personal ruminations. His title was inspired by a fragment of the writings of the ancient Greek philosopher Anaximander (circa 600 B.C.): “Things are transformed one into another according to necessity, and render justice to one another according to the order of time.” In response, Rovelli’s book asks, Why should time have an order? And for whom? And to what end?

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Carlo Rovelli and Benedict CumberbatchCreditAnnabel Huxley

Prior to Einstein, it was believed that time was absolute. A second was a second was a second, period. Time flowed in lock-step uniformity everywhere throughout the universe. The idea was so obvious as not to be questioned — until it was. In 1905, at age 26, Einstein first set out to explain the workings of electricity and magnetism. In the process, he proposed that identical clocks in motion relative to each other do not tick at the same rate. That seemingly absurd proposition has been proved. Later, Einstein conjectured, with a highly mathematical theory called general relativity, that gravity also affects the rate of ticking of clocks: A clock in strong gravity ticks more slowly than one in weak gravity. That claim has also been proved. The final insult: Two events that are simultaneous to one person are not for another person who is in motion with respect to the first. Thus the entire concept of “now” needs rethinking.

Chapter by chapter, Rovelli shows how modern physics has annihilated common understandings of time. And both the writing and vocal delivery are beautiful.

“Time is not a line with two equal directions: It is an arrow with different extremities. And it is this, rather than the speed of its passing, that matters most to us about time. This is the fundamental thing about time. The secret of time lies in this slippage that we feel on our pulse, viscerally, in the enigma of memory, in anxiety about the future. This is what it means to think about time. What exactly is this flowing? Where is it nestled in the grammar of the world?” Here Rovelli is raising yet another of time’s mysteries. Why does it have such a clear directionality, with the future so easily distinguished from the past?

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Let me explain. If you see a film of a teapot first sitting on the edge of a table, then falling off the table and shattering into a thousand shards, the film appears perfectly normal. Evidently, someone jostled the table. But, if you were to watch a film in which shards of pottery scattered about on the floor suddenly rushed together and formed a teapot, which then jumped up to land on a table, you would interpret that film as being played backward in time. Because you’ve never seen such a sequence of events in the real world. Why not?

The answer is a matter of probability. A broken teapot could indeed re-form itself from vibrations and heat in the floor, but it is highly unlikely. Physics shows that moving from order to disorder is more probable than the reverse — much more probable when it comes to large collections of atoms such as constitute a teapot. In scientific terms, this movement determines the direction of time. And the fact that this direction is so definite in all that we see, both on earth and beyond, means that the cosmos must have begun in a state of relatively high order — with plenty of room to make a mess in the future. It is that room for increasing chaos that drives the evolution of the universe, that drives change. Without it, stars and planets would never form, humans and other life-forms would never exist, and teapots would never be made in the first place, broken or otherwise.

Physicists still do not understand why our universe appears to have been created with such a high degree of order. Rovelli suggests that it’s a matter of our human “perspective,” and depends on our “interactions” with the physical world. I respectfully disagree. It is theoretically possible for the universe to have been created in a state of nearly maximum disorder, in which case no evolution or change would occur. That would not be a matter of perspective. One possibility, entertained by a number of leading physicists, is that there are lots of universes, the so-called multiverse, with very different properties and initial conditions. Some of those universes may have started in conditions of maximum disorder, with nothing driving change, no distinction between future and past, where atom-size pottery shards gather themselves up to form atom-size teapots as often as the reverse. But some of these universes would have been created, by accident, with relatively high order. We live in such a universe because otherwise we wouldn’t be here to discuss the matter. The theory of “quantum gravity,” which is still not fully formulated, describes such a continuous creation of universes with random properties and initial conditions.

Some elements of Rovelli’s narrative, like the material on light cones and loop quantum gravity and spin networks, many readers will find incomprehensible. But the many other excellent explanations of science, the heart and humanity of the book, its poetry and its gentle tone raise it to the level and style of such great scientist-writers as Lewis Thomas and Rachel Carson. Listening to Rovelli’s book, as read by Cumberbatch, we hear the warm voice of a modest man searching to understand not only the physical world but also how he, and we, perceive it. “Time, then, is the form in which we beings whose brains are made up essentially of memory and foresight interact with the world,” Rovelli writes near the end. “It is the source of our identity.”

Alan Lightman is a physicist, novelist and humanities professor at M.I.T. His latest book is “Searching for Stars on an Island in Maine.”